In a mobile communication system, a received-signal state (for example, received power and reception quality) within an area of a base station changes as a result of a building being constructed within the area, and the like. Thus, an operator conducts a drive test for collecting location information at the time of measurement while measuring a received-signal state by using a vehicle for measurement loading thereon measurement equipment.
When the operator discovers a location or an area where a received-signal state deteriorates (that is, a coverage problem) through the drive test, the operator performs network optimization for resolving the discovered coverage problem. Herein, network optimization refers to, for example, changing a parameter of a base station, and newly installing a base station.
The drive test has the problem of too many man-hours and high cost. Thus, according to 3GPP (3rd Generation Partnership Project), which is a project aiming to standardize mobile communication systems, the standards determination of MDT (Minimization of Drive Test) for automation of measurement of a received-signal state and collection of location information, is being progressed by using a radio terminal belonging to a user (see Non Patent Literatures 1 and 2).
The radio terminal set (configured) to perform MDT measures a received-signal state and reports, to a mobile communication network, measurement data including information related to the measurement results and location information at the time of measurement. MDT performed when a radio terminal is communicating is referred to as immediate report type (Immediate MDT), and MDT performed when a radio terminal is in a standby state is referred to as record-type (logged MDT).